Synthesis and Gelation Behavior of Phosphorus-containing Cholesterol-based Low Molecular-mass Organic Gelators

Three new cholesterol-based gelators bearing a phosphorus unit have been synthesized and characterized. These compounds were synthesized by letting quinol phosphoric acid ester reacted with cholesterol, cholesteryl glycinate or 3 beta-cholest-5-en-3-yl N-(2-aminoethyl)carbomate (denoted as compound 1, 2, and 3, respectively). The gelation behaviors of them in 35 solvents were evaluated. It was found that 1 is a very weak gelator, and only CHCl(3) can be partially gelled. Compound 3 gels n-pentane to n-decane, but n-pentane is in a partial gel state. Compound 2, however, gels both protic (n-pentanol to n-decanol) and aprotic solvents (n-pentane to n-decane, and cyclohexane). Scanning electron microscopy (SEM) measurements revealed that the xerogel morphology of a gelator depends upon the structure and concentration of the gelator, and the nature of the solvent as gelled. Further more, the stacking mode and the interaction nature of the gelator molecules in the gels were studied by FTIR spectroscopy measurement and XRD analysis.